Old CINT was not able to parse them correctly

Old CINT was not able to parse includes, therefore protection was required

CINT was not able to parse them correctly

These includes may be used in dictionaries and therefore should
be available already in core libs

In TEntryList::Remove and TEntryList::GetEntryAndTree the error case of GetEntry (received
indirectly by TEntryList::Remove) was not treated and consequently 'undefined' behavior
followed.  stressEntryList triggered a crash in GetEntryAndTree when reading random
memory to fill the input TTree led to a situation where a TEntryList was created on a
large chain but then applied to only a subset of that chain __and__ the selection/random-number
was such that none of the entries of the subset was selected (but some of the other part of
the large chain was selected).  This lead GetEntryAndTree to call GetEntry in a state that
it returned an error code (-1) and left the TEntryList in a state unexpected by GetEntryAndTree
(namely that fCurrent is nullptr even though fLists is not nullptr)

Due to the previous random memory address read, we ended up testing a new content layout that
we are reproducing now with a 'fixed' cut.  In this test, we first create a TEntryList
from a large chain but apply it to a small chain but none of the entries in the small tree was selected
then it triggered a crash in TEntryList

This is a follow up of f5249760 and a fix for ROOT-10632

Fix discrepancy with find_package_handle_standard_args and  name of the calling package (CMake 3.17)

While gtk sources are in ROOT source directory, one needs
to specify includes from ${CMAKE_SOURCE_DIR}.
This is not good, while dictionaty intend to be build only from
${CMAKE_BUILD_DIR}/include.

Was required in previous usage, now they are fully internal

One need virtual method in TVirtualIndex to verify if it can be
applied to TTree. Otherwise one has to link Tree lib again TreePlayer and
Hist to access TTreeFormula methods, making circular dependency

[ROOT-10647] The "section" argument of the function was ignored.

This patch also instruct the build system to not copy {libc,std}.modulemap in
OSX because the standard libraries are already modularized.

Fixes a regression introduced by root-project/root@603a1c3e96

On linux, the compiler flags are cache variables, i.e. they can be
overridden by the user. On Mac, that wasn't the case.

rootcling writes dependency information which is never read/used when
loading the rdict file.

Otherwise one has to set dependency from ProofPlayer lib

Let use this enum in win32gdk to avoid direct dependency from
Gui library there

It is a proper place for virtual class

Includes are from libs, which are not in Hist library dependency list